Training for a Half IronMan

Training for a Half Ironman Triathlon

By Ken Mierke and Joe Friel

This is a  repost from

The half ironman triathlon presents unique challenges. This distance is short enough that a well-conditioned athlete pushes throughout the race, but long enough to demand disciplined pacing and effective nutrition strategies. Preparing for a half ironman requires balancing long workouts, designed to improve endurance, with higher intensity workouts, designed to increase the pace that can be maintained for the race duration. Half ironman racing also requires plans for effective fueling, hydrating, and pacing.


The two key workouts for a half ironman triathlon are both brick workouts (bike followed by run). The first is a long brick workout at an easy pace. The second is a race-pace brick workout.

A half ironman is a relatively long race. The endurance to hold up for race duration is always the triathlete’s most important ability. A brick workout at a basic endurance pace, gradually increasing in duration, is key for building that endurance.

Begin with a one-to two-hour ride followed by a 30-minute to one-hour run. Experienced athletes who have already developed a solid endurance base can start at the high end of the range. Gradually build the duration of these workouts until a three- to four-hour ride followed by a one- to two-hour run is comfortable. These workouts should be completed at a basic endurance pace (zone 2 in the Training Bible system of monitoring intensity). Both the ride and the run should take place on flat to gently rolling terrain so that intensity can be kept under control. This workout is the priority during the base period.

After establishing a solid endurance base, a race-pace brick becomes the priority workout. This workout increases cycling and speeds that can be maintained for the half ironman distances. During your build phase, perform one of these workouts each week.

Workout intensity is based on each athlete’s ability. Beginner triathletes should be more concerned about developing the endurance to finish a half ironman than about speed. On the other hand, intermediate and advanced triathletes are not worried about being able to finish, but are concerned with the pace that they can maintain for the duration.

Begin with a ride of about one hour at endurance pace (zone 2). After the hour is up, increase speed and attempt to maintain the intensity that can be sustained for the duration of the half ironman race. For beginning athletes, this will be at endurance pace or just slightly faster. For intermediates, this will be somewhat faster than endurance pace and will probably fall in the upper half of heart rate zone 3. Advanced athletes will maintain sub-threshold pace, approximately five to eight beats per minute below lactate threshold, in the lower half of heart rate zone 4. Increase this workout conservatively, monitoring recovery closely. It can bring quick improvements, but can also lead quickly to overtraining.

Do this workout on terrain similar to the race course. Keep intensity steady and maintain relatively high cadence. Eat and drink exactly according to your race plan. Maintain the intensity that you could realistically hold for race duration. Harder is not better.

Begin running as soon after the ride as possible. For the first segment of the run, hold the pace that feels sustainable for race distance. Continue to eat and drink as you will during the race. Finish the workout with at least 20 minutes of easy running.

Begin using 30- to 45-minute, race-pace segments on the bike and 20- to 30-minute, race-pace segments on the run. Increase duration of the race pace segments consistently, but gradually. These workouts develop efficiency at race intensity and allow practicing the skills of pacing, hydrating, and fueling.

Race-pace workouts should never approach race duration. Even advanced athletes should build up to no more than 50 percent of race duration at race pace. Full efforts should be saved for race day. The time required for recovery from huge efforts, such as 75 percent of half ironman distance at race pace, is not worth the benefit. Save those full efforts for race day and concentrate on consistent and efficient training until then.

Fueling and Hydrating

For an international-distance triathlon, most of the energy to be expended is already stored in the body at the start. While fueling and hydrating during those races can be important, they become even more important at the half-ironman distance, when much of the required fuel must be consumed during the race.

Fueling begins hours before the race, at breakfast. The goal is to provide the body with adequate fuel without overloading the digestive system. Practicing this before workouts is critical. We can provide guidelines, but every athlete is different and finding the unique combination of foods that work best for you is a trial and error process. Consume 400 to 800 calories about three hours before a half ironman. Try to consume one gram of protein for every three to four grams of carbohydrate.

Consuming water and carbohydrate immediately pre-race can benefit as well. Obviously fueling and hydrating during the swim are impractical, but food and water consumed directly before the swim start can be delivered to the working muscles during the swim. We recommend consuming 100 to 300 calories of carbohydrate and 8 to 12 ounces of water immediately before the start. Make sure to consume this last feeding as soon before the start as possible. This prevents an insulin response leaving blood sugar low at the race start.

On the course, hydration is a top priority. A 150-pound athlete should consume 20 to 30 ounces of water per hour. Take this very seriously. Follow a plan and do not rely on thirst. Drink water or sports drink approximately every 15 minutes. The excitement of the race atmosphere can work against you in this area. Some athletes find it effective to set a watch to beep every few minutes to remind them to fuel and hydrate.

During a half ironman, a triathlete should consume as much carbohydrate as can be digested and absorbed. For most athletes who have practiced fueling strategies during training, this amounts to about 300 calories of carbohydrate per hour for a 150-pound athlete. Each athlete is different, so experiment with this during workouts to find out how much your digestive system can handle. Find how much carbohydrate you can digest without it sitting in your stomach.

Immediately after the race, providing the body with nutrients required to refuel and to rebuild damaged tissue is critical to minimize recovery time. Make sure to consume at least 400 calories of carbohydrate and 100 calories of protein right after the race. Several excellent products designed to be used immediately post-workout are on the market.

Race Strategy

Very few athletes finish a half ironman thinking that they didn’t go hard enough early in the race. Consistent pacing is necessary to perform to your potential. Pace conservatively, especially during the first half of the bike and the first half of the run. A triathlete who rides two minutes too slowly during the first half of the bike has the opportunity to gain back most of that time. A triathlete who rides two minutes too fast will lose much more than two minutes on the run.

Race pace workouts will teach you the intensity that can be sustained on race day. Even though workouts didn’t approach race duration, a full taper plus the excitement of the race atmosphere usually allow a pace to be sustained longer. The effort that enabled effective running after the bike during workouts should do the same in the race.

Intensity should be steady throughout the race, but perceived exertion will gradually increase. The correct pace will feel easy early in the race. The same speed feels quite different at mile 10 of the bike than at mile 50. Performing to your potential is never easy, even on the best days.


A correct taper increases a triathlete’s fitness dramatically. In the last several weeks before an event it is too late to significantly increase fitness, but it is not too late to increase fatigue. After a significant taper, athletes store more fuel, deliver more oxygen to muscles, and maintain higher intensities than would have been possible before the taper. Reducing training for two to three weeks before the race will not reduce fitness. Rest!

Hard training athletes should use a gradual three-week taper. Heavy training for a half ironman leaves deep levels of fatigue. We recommend reducing training volume to about 70 percent of normal beginning three weeks before the race, to about 50 percent two weeks before the race, and to about 40 percent the week of the race. It is important to maintain some intensity. Dropping all intensity during a taper reduces red blood cell volume and decreases the efficiency of movements. Reduce workout duration, but maintain segments at race pace several times per week. A shortened version of the race-pace brick done every 72 to 96 hours will do this nicely while allowing you to rehearse your pacing strategy, also.

A half ironman can be an exhilarating experience when proper training, taper, nutrition, and pacing strategies all come together on race day. This requires planning, discipline, and hard work, but aren’t those all part of what triathlon is all about?

Ken Mierke and Joe Friel are both Ultrafit coaches. Ken’s business, Fitness Concepts, is in Annandale, VA. Joe Friel is the author of the The Triathlete’s Training Bible. Article originally published for Inside Triathlon.